Nuclear and Chemical Waste Management最新文献

Leaching of chromium in solidified cement indicates that the release of chromium(III) corresponds to the solubility of the hydrolized compounds Cr(OH)₃ which presents a low constant value (10⁻⁶ Moles L⁻¹ over a wide pH range. On the other hand, high soluble Cr(VI) presents in the first period of leaching a kinetic release similar to that previously observed for calcium. In addition, physical tests have been carried out on cement blending variable amounts of chromium compounds. The results concerning the compressive strength, densities, and porosity of cement containing CrCl₃, Cr₂O₃ and Cr0₃ are reported and discussed.

The analysis of lead, zinc and cadmium in Bahrain refinery sludge collected from various deposition sites at Bahrain petroleum company (BAPCO) are reported. Atomic Absorption spectrophotometric method, both flame and flameless (graphite furnace) techniques, were used for the analysis. The concentrations of lead, zinc and cadmium were found in the range, 66.1 to 14630.9 mg/kg (0.007% to 1.46%), 47.4 to 1791.1 mg/kg (0.005% to 0.17%), 0.24 to 5.40 mg/kg (0.00002% to 0.0005%), respectively. These concentrations are less than 1% as is accepted internationally. Nevertheless, these are hazardous and should be managed properly.

This study was conducted to evaluate the utility of short-term microbial bioassays to assess the mutagenic hazard of an uncontrolled hazardous waste site, and to compare the results from chemical and biological analysis of split soil and water samples. The results from chemical analysis indicated that the greatest concentration of contaminants was present in samples from an oil-stained area, and from the vicinity of a PCB disposal area. The results from the analyses of mutagenicity of these samples indicates that these samples also had the greatest specific activity, inducing 155 and 140 net revertants when the methylene chloride and methanol fractions were assayed, respectively. However, when the samples are compared on the basis of weighted activity, the sample from the vicinity of the PCB disposal area had the maximum activity (2410 revertants per gram of soil). While a second sample from the vicinity of the PCB disposal area had a weighted activity of 757 revertants per gram of soil, it contained no organic constituents which could be identified using standard analytical procedures. These results indicate that a combined testing protocol using both chemical and biological analysis will provide a more accurate data base from which to make a risk assessment than the use of either method alone.

The equilibrium distribution coefficient K for mixed phenols, between coking plant wastewater and tert-amyl methyl ether (TAME), is determined. The effect of pH upon the distribution K of pure phenol is measured in the buffered water solution-phenol-TAME system. Laboratory and pilot plant results of continuous countercurrent extraction of mixed phenols from coking plant wastewater are reported.

The adsorption tendency of leached-out ²³⁸Pu and ²⁴⁴ Cm on the wall of leach containers, during the leaching of waste glasses, was studied. The test pieces of quartz glass, PFA Teflon, gold and stainless steel, which are candidates for a leach container, were immersed in deionized water with the waste glass containing ²³⁸Pu or ²⁴⁴ Cm in a Pyrex glass container at 100°C, and then they were decontaminated with dilute nitric acid. The quartz glass was found to have the smallest contamination of ²³⁸Pu and ²⁴⁴CM. The adsorption amounts of ²⁴⁴Cm on the PFA Teflon and quartz glass were approximately the same, and for ²³⁸Pu the Teflon showed about twice the amount of adsorption as that measured on the quartz glass. The gold and stainless steel showed 30–40 times the adsorption amount of ²³⁸Pu as that on the quartz glass. Adsorption and desorption of curium and plutonium were discussed in relation with difference of materials, time dependence and acidity of leachate. Curium, which has been previously leached out from waste glasses, showed a relatively simple adsorption and desorption behavior. In the case of plutonium, the colloidal species would take a large part in the adsorption and desorption processes. The relationship between the ratio of the colloidal to the ionic species of plutonium and the adsorption-desorption behavior was discussed. The observation of alpha autoradiographs elucidated that the ionic adsorption was desorbed more easily than the colloidal one.

A finite element model is developed for delineating radioactive contaminant plumes via groundwater. The model is then used to predict the migration of ²²⁶Ra and U from the near-shore Port Granby waste management site to Lake Ontario. The model runs are made simulating either one or two stratigraphic layers and simulating varying degrees of anisotropy in each layer. The model-predicted ²²⁶Ra and U concentrations are found to be in good agreement with those actually observed. Recovery phase analysis predicts that the continuous migration, via groundwater, of both contaminants toward Lake Ontario is likely to persist even after the waste is removed from the site.